1. Field of the Invention
The invention relates to a device for detecting the support load with which a tongue of a trailer vehicle acts on a tractor vehicle.
2. Related Technology
There is a need in precision agriculture to detect the weight or the mass of the loads of trailer vehicles. The load can be harvested material that is placed on the trailer vehicle, e.g., in the case of a trailer vehicle in the form of a transport trailer during the harvesting of beets or fodder, or that is pressed to bales in the trailer vehicle, e.g., in a trailer vehicle in the form of a bale press during the harvesting of hay, straw or silage. A position-specific yield chart can be made using the weight values recorded in a geo-referenced manner at certain time intervals.
Since the successive weight changes are at least as relevant as the cumulative total mass, the highest-possible precision is desirable when detecting the weight.
Various devices are known in the state of the art for measuring mass of the load. WO 97/09592 A suggests placing several measuring cells between the loading surface of a transport trailer and its undercarriage. DE 199 06 611 A analogously suggests arranging measuring cells between the pressing chamber housing of a bale press and its undercarriage. Such an arrangement requires that the tongue is also to be connected below the loading surface to the undercarriage. However, in bale presses the pressing chamber housing forms part of the undercarriage so that such an inclusion of measuring cells means a completely new construction of the trailer vehicle, in particular of the bale press.
DE 195 43 343 A suggests detecting the weight forces acting on the axles and the traction tongue of a bale press. The weight force of the bale produced is calculated using the change in forces during the ejection of the bale. DE 102 45 001 A describes an analogous arrangement of the measuring cells in a vehicle for discharging biomass.
The measuring cell built into the traction tongue is intended to detect the vertical load of the traction eyelet, that is, the support load, with which the traction tongue acts on the coupling of the traction vehicle. It is thus arranged in the vertical direction between the traction tongue and the traction eyelet. However, its output signal can be influenced by horizontal forces acting between the trailer vehicle and the tractor vehicle. Errors of measurement can occur thereby, in particularly through tilting of elements that can move relative to each other in the vertical direction if rather high braking forces or tractional forces are active.
DE 203 13 356 U describes a support device for the trailer tongue of a passenger car trailer. A spring is arranged inside a tube, the expansion of which spring is a measurement for the support load with which the trailer tongue acts on a support wheel. The upper end of the spring is connected to the trailer tongue while its lower end is connected via an oscillating arm to the support wheel. The oscillating arm is mounted in such a manner that it can rotate about a horizontal shaft parallel to the axis of rotation of the support wheel. This is intended to avoid a tilting of the movable parts connected to the support wheel and to improve the measuring accuracy. The support force of the support wheel is measured here. Thus, this measuring device is not suited for determining the support load or contact force with which a tongue acts on a coupling of a tractor vehicle.